docs: add sub section titles

Author: kenjis

user_guide_src/source/libraries/sessions.rst

@@ -559,6 +559,9 @@ However, there are some conditions that must be met:
 Configure DatabaseHandler
 -------------------------
 
+Setting Table Name
+^^^^^^^^^^^^^^^^^^
+
 In order to use the 'DatabaseHandler' session driver, you must also create this
 table that we already mentioned and then set it as your
 ``$savePath`` value.
@@ -567,6 +570,9 @@ you would do this:
 
 .. literalinclude:: sessions/039.php
 
+Creating Database Table
+^^^^^^^^^^^^^^^^^^^^^^^
+
 And then of course, create the database table ...
 
 For MySQL::
@@ -594,6 +600,9 @@ For PostgreSQL::
     and the session ID and a delimiter. It should be increased as needed, for example,
     when using long session IDs.
 
+Adding Primary Key
+^^^^^^^^^^^^^^^^^^
+
 You will also need to add a PRIMARY KEY **depending on your $matchIP
 setting**. The examples below work both on MySQL and PostgreSQL::
 
@@ -611,6 +620,9 @@ You can choose the Database group to use by adding a new line to the
 
 .. literalinclude:: sessions/040.php
 
+Setting Up Database Table with Command
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 If you'd rather not do all of this by hand, you can use the ``make:migration --session`` command
 from the cli to generate a migration file for you::